In a mobile communication network, Mobile Signaling Implementation Function (MSIF) known as Mobility Management Entity (MME) can control overload in cooperation with the base station. At this time, the MSIF may control the overload using the Radio Resource Control (RRC) Establishment Cause transmitted from the base station to the terminal for a certain service.
FIG. 1 is a diagram illustrating a wireless communication system for controlling overload according to a conventional technology.
As shown in part <a> of FIG. 1, if overload caused by the service to the terminals, the MSIF sends the base stations overload start messages 310a and 310b for controlling overload along with its overload information and overload control information. Then the base stations perform overload control according to the message from the MSIF. If the overload is mitigated through the overload control procedure, the MSIF sends the base station an overload stop message 120 for terminating the overload control as shown in part <b> of FIG. 1.
FIG. 2 is a diagram illustrating a control message per overload rank according to the conventional technology.
Referring to FIG. 2, the overload control message may control to permit RRC connection in response to an RRC Connection Request message received from the terminal. In order to accomplish this, the overload control message includes configuration information indicating whether to permit or reject the RRC connection depending on the RRC Establishment Cause value included in the RRC Connection Request message. The RRC Establishment Cause value is the information on the service to be provided to the terminal.
As shown in FIG. 2, the RRC Establishment Cause value defines delay tolerant 210 for Machine Type Communication (MTC) terminal, mo-Data 220 for outgoing call service, mo-Signaling 230 for voice service provided due to Circuit Switching (SC) fallback, high Priority Access 240 for specific user, mt-Access 250 requesting for network for incoming call service, emergency 260 for emergency call service, etc.